Fuse



Oct. 7, 1947. H. J. NICHOLS FUSE Filed Jan. 27; 1941 Patented Oct. 7, 1947 UNITED STATES PATENT OFFICE FUSE Harry J. Nichols, .Binghamton, N. Y.

Application January 27, 1941, Serial No. 376,231

6 Claims.

This invention relates to point. detonating fuses especially designed for small anti-aircraft projectiles and the like, and will be described with relation to such application although it is to be understood that without material modification many features are equally applicable for other uses.

Detonatin fuses for small anti-aircraft projectiles, say in calibres of 20 mm. to 3'7 mm. inclusive, present particular difiiculties because of their small size and the great accelerating and centrifugal forces to which the parts are subject in firing and in flight. It is essential that fuses for this purpose be extremely sensitive on impact, yet at the same time they must be entirely safe in handling and firing. Because of the great force .of acceleration or set-back on firing, the detonator may be fired by concussion While the projectile is in the bore of the gun. This makes a bore-safe feature highly desirable. A fuse to be bore-safe must have adequate provisions against arming in the bore of the gun, and in the event the detonator is exploded by concussion due to firing of the gun, the explosion must be so limited as not to disrupt the fuse nor to cause explosion or break-up of the projectile.

A further desirable feature is that the fuse be not completely armed until the projectile has travelled a short distance beyond the muzzle of the gun, since a relatively strong retarding force acts on the projectile when it strikes the air on emerging from the gun, and if the sensitive firing elements can be thrown together at that instant, premature detonation may result. This. feature is usually termed a muzzle-safe feature.

To ensure adequate sensitively and quickness on impact with light targets, such as wing covering of aircraft, the impact element must be of light weight, and dynamically balanced with respect to the axis of rotation. The design should be such that the impact element first strikes the target, and as this element is thereby retarded, the projectile drives the detonator into the firing pin, producing instantaneous detonation before the projectile has been sensibly retarded. This is termed super-quick action.

Finally, from the practical standpoint, fuses of this class should be extremely simple and rugged in construction, easily loaded and assembled, and adapted to low cost manufacture in large quantity.

It is therefore one of the principal objects of this invention to meet in a highly eflicient, reliaexplosive to form the booster I3.

ble, and practical manner the general and special requirements above stated.

Another object is to provide simple and reliable bore-safe and muzzle-safe arming means which utilize forces generated by firing in a rifled gun, but which complete the arming process only after the projectile has left the bore of the gun.

Another object is to provide detonator arming means which is rotated by centrifugal force to turn the detonator to armed position but which is inherently incapable of being thrown from such armed position thereafter.

Other objects will be in part obvious from the annexed drawings and in part hereinafter indicated in connection therewith by the following analysis of this invention.

This invention accordingly consists in the features of construction, combination of parts, and in the unique relation of the members and in the relative proportioning and disposition thereof, all as more completely outlined herein.

In the drawings forming a part of this disclosure, like characters of reference denote corresponding parts throughout the several views, in Which Fig. 1 shows in longitudinal cross section a point-impact, detonating fuse illustrating one embodiment of the invention, the mechanism being shown in unarmed condition.

Fig. 2 is a transverse cross section of the fuse shown in Fig. l, the section being taken at the plane indicated by line 2--2 in Fig. 1.

Fig. 3 shows the same fuse as in Fig. 1, in the same section, the mechanism being in armed condition.

Fig. 4 is a transverse cross section of the fuse shown in Fig. 3, the section being taken at the plane indicated by line 4-4 in Fig. 3.

Figs. 5 and 6 are front views of the rotor exterior, showing the position of the segments in unarmed and armed conditions respectively.

Fig. '7 is a fragmentary section of the nose of the fuse showing the firing pin arming mechanism during set-back.

Referring now to these drawings, and particularly to Fig. 1, the main structural element of the fuse is the body It), with external screw threads H for assembly to the projectile (not shown). In the base of the body is a cylindrical cavity adapted to house the booster cup l2, the latter being filled with a charge of compressed The loaded booster cup I2 is held securely in place by a spunover lip l4 formed from the fuse body at assembly, as shown, or otherwise as desired. The forward position of the body is provided with a cylindrical 'bore adapted to receive the rotor housing l5 (Fig. 2), the support disc l5, and the shouldered end of the nose-piece ll. Extending from the bore to the booster cavity is a smalldiameter, axial hole, counter-bored at the upper end to receive cord cu-p l8. The interior of the cup and the axial hole are filled with tightly compressed explosive to form; the d'etonatingcord I 9;

The rotor housing l5. has a rectangular bore in which is mounted a rotor 20, Figs. 5 and 6, of short cylindrical form and lying edgewise in the bore. This rotor 20 has a diametral round hole adapted to receive a detonator 2| (preferably contained in a thin capsule) and a small, tapered hole 20h, located at an a gle of approximately 45 to the axis of the hole for the detonator 21-.

The rotor is of a special form, so that while it is virtually statically balanced as it lies unarmed in the housing, it is symmetrically dynamically un-. balanced with respect to the axis of they fuse, which is likewise the axis of rotation of the projectile.

Referring to Figs. 5 and 6, on each end of rotor 20;. a diametral channel 290 is cut or formed at a slight inclination, say to the axis of the detonator 2|. This leaves tWo segments. 2.9.x 01.1. each end of the rotor which segments mainly produce the dynamic unbalance. Upon rotation of the fuse about its. axis, a torque couple tending to. turn, the rotor about its own cylindrical axis 20a in a counter-clockwise direction as indicated by arrows is produced because of this dynamic unbalance. There isv also some minor dynamic unbalance due tothe; difference in specific gravity of the loaded detonator capsule and the rotor metal, but the rotative effect produced thereby is inefiective, and the segments may be considered to produce the torque effect. The inclination of these segments to the detonator hole, previously mentioned, sufiices to overcome minor unbalance and friction, so that after being fired in a gun the longitudinal axis of the detonator 2| indicated in dotted line is aligned with the aXis of the fuse as shown in Fig. 3. Once in this position, the rotor is inherently in a dynamically stable condition.

Referring again to Fig. 1, the nose-piece IT has an axial counter-bored hole adapted to receive the set-back cap 22 and the firing pin 23. The cap is provided with an internal bore, slightly smaller in diameter than the firing pin 23 except for part of the slight taper in the mouth. of the bore. The firing pin is provided with a cross slot 235. The construction is such that while at assembly the slotted end of the firing pin can be Entered into the. mouth of the cap, a substantial force is required to. force the cap completely over the firing pin as shown in Figs. 3. and '7. It will be understood thatby proper design of the fit of the cap. on the firing pin, the material of the firing pin, and the width and depth of the slot 23s, the force necessary to push the cap down over the firing pin can be established at a safe but operative value to suit various applications.

Between the rotor housing I5 and the nosepiece Ilis assembled a thin but strong metal disc, termed the support disc it, having an axial hole IBh (Fig. 3) of such size as. to fit snugly the taper point 23p of the firing pin 23. In unarmed position, point 23p rests in hole 2th of the rotor, preventing turning of same.

A cover 25 fits tightly over the body and nose assembly, being spun over at the lower edge as shown. A thin, domed diaphragm 24, assembled between the nose-piece and the upper rim of the cover, seals the assembly at the point. Following usual practice, suitable cements or sealers are applied at the joints between body and booster cup, body and nose-piece, and nose-piece, cover and diaphragm to seal hermetically the completed assembly.

Referring now to Figs. 1 and 3, the operation of; the fuse is as ollows: Qn firing-in a gun, due to the set-back force, cap 22 slips over the shank of the firing pin 23 as shown in Fig. 7. The same force causes the firing pin point to remain in the hole 20h in the rotor, preventing the rotor from turning about its own axis. Hence the rotor 20 remains in the position shown in Fig. 1. When the projectile emerges from the muzzle of the gun, the projectile strikes the exterior air and is materially retarded thereby, tending to project interior elements towards the point. This is known technically as creep. The, dome 2A is ad t o ough to, Withstandset-back. and the exterior ir re sure. in fli witho bein deformed thereby. Hence the. cap and firing pin, n w w ed to eth r. and. not be n s bject. to. the. air pr ssur w 11. r ep forward nto the posttion shown in Fig. 3. Upon being released by the, firng pin. 23, the rot r 20. turns about. its. transverse or cylindrical axis, bringing the, detonatgr t i nm nt. wit he firin point. 31;. and detonating cord I3. The fuse is now completely armed as shown in Fi 3..

On impact with. the targetcven though it be a flimsy one such as. the coverin on. an airplan the, dome 24. and the cap. 22 will be driven wardly, stabbing thefiri point 23 into. the, detonator 2|, and exploding same. Thereupon thedetonating Wave is; transmittfid instantly to.

. target.

Consider now. the action of the rotor 20 tor; bore-safety. While the projectile is in the gun, the set-back force and the firing pinpoint both func ion to pre ent the, rot r turn n Should the. detonator 2|. be exploded by the, shock. of firing... h owe rim r th r tor w ll b wed ed, nto. t ord o l e aval e. nd the. explos ve ases will be vented into the voids. in they u e without disrupting th f 0r exp odi g the booster .3-. Should the acceleration of the projectile, be rep. versed in direction. due to. coppering or other ob; struction in the gun bore, the rotor would tend t be t n rwa d. ikew s t e fir n p n would. be projected forward. But the linear and angular retardation forces, WOU-ld bind. the rotop in its housing and prevent its turning. Hence-it s vident that. u d r conee v bla cirqume stances n; the detonate? becom efi tiv to armed position. Hence the usual locking means characteristic of detonator arming means can be dispensed with.

It should be evident from the foregoing that the invention provides novel and advantageous features in arming means for fuses, and that the invention as a whole adequately meets the general and special requirements for fuses of this class.

Without further analysis the foregoing will so fully reveal the gist of this invention that others can, by applying current knowledge, readily adapt it for various applications without omitting certain features that, from the standpoint of the prior art, fairly constitute essential characteristics of the generic or specific aspects of the invention, and therefore such adaptations should and are intended to be comprehended within the meaning and range of equivalency of the following claims.

I claim:

1. In a point impact detonating fuse for small rotative shells, in combination, a body member adapted to carry a booster charge, a nose' member, an impact firing pin longitudinally mounted in said nose member, a setback arming cap adapted to slip over the head end of the firing pin on setback, a centrifugally actuated detonator carrying member normally holding a detonator obliquely with relation to the impact firing pin when the fuse is at rest, and able to rotate said detonator into line with the impact firing pin after the setback arming means and firing pin creep forwardly when the fuse is in flight.

2. In a point impact detonating fuse for small rotative shells as set forth in claim 1, in which said detonator carrying member includes a relatively fiat, cylindrical member having its cylindrical axis transverse to but in line with the longitudinal axis of the fuse.

3. In a point impact detonating fuse for small rotative shells, detonating mechanism including an axial firing pin and a detonator, and safety arming means therefor comprising a cap slidable over the forward end of the firing pin by set-back at firing, and a centrifugally actuated cylindrical detonator rotor mounted with its axis transverse to the axis of the fuse and normally held against rotation by said firing pin but rotatable by centrifugal force after firing.

4. A point detonating impact fuse for use with a rotative explosive shell for rifled guns, comprising a pointed housing structure adapted for assembly with said shell having an explosive booster charge sealed in a cavity in the base thereof and a sealed axial bore in the point thereof, an axially extending impact striker having a firing pin at the inner end thereof and slidably housed within said bore, a cylindrical detonator positioned on the axis of rotation of said structure intermediate said firing pin and said booster and normally inclined in safe relation to both, centrifugally actuated rotor means for holding said detonator in safe position and for turning said detonator into alignment with said firing pin and said booster after said shell is fired in a rifled gun, and safety means for retaining said firing pin and said rotor means in safe position until after said shell is fired in a gun.

5. In a point impact detonating fuse for small rotative shells, in combination, a body member, a booster charge mounted therein, a nose member attached to said body member and having an axial bore sealed at the point and an axially extending impact firing pin housed therein, a detonator, centrifugally actuated rotor arming means therefor housed in said body member, and setback actuated safety means for normally retainin said rotor in safe position including the firing pin and a hollow cylindrical member adapted to be forced over the forward end of said firing pin by set-back force.

6. In a point impact detonating fuse for small rotative shells, in combination, a body member, a booster charge mounted therein, a nose member attached to said body member and having an axial bore sealed at the point and an axially extending impact firing pin housed therein, a detonator, centrifugally actuated arming means therefor housed in said body member including a cylindrical member carrying the detonator in a bore in one of its diametrical axes and having at least one slot cut into an end wall thereof whereby, on firing, said detonator under the action of centrifugal force on said member will be moved into line with said impact firing pin, and set-back actuated safety means for normally maintaining said cylindrical member in safe position.

HARRY J NICHOLS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,774,043 Summerbell Aug. 26, 1930 1,342,652 Sullivan et a] June 8, 1920 1,687,341 Lukens et a1 Oct. 9, 1928 2,155,100 Scelzo Apr. 18, 1939 FOREIGN PATENTS Number Country Date 95,932 Sweden June 6, 1939 525,053 Germany May 19, 1931 

